My dataaqusition system using USB interface to computer. I am using 18F4550to do that.

My device has separate power ,I need a LED to glow in hardware and the software needs to detect System when plugged.
My hardware needs to be clean from the SMPS noise or ripple or whatever from computer power supply.

What is the best and effective filer mechanism to use on USB connectivity?

Do we need to connect the ground of USB connector to my board ground. Also I need to connect the Vcc of the USB connector to MCU So that firmware can detect host plugged.
In this case Gnd needs to be conected.
Any filetr mechanism here?

If you have separate power supply, there's no need to connect the Vcc. USB detection does not depend on the Vcc sensing, but on pulling D+ and D- lines to a certain voltage.

Click to expand...

My system connects to PC only at the time of data uploading. If a pin is used to detect the USB connector Vcc, the USB engine needs to be started only at the time of plugin to start enumeration.
Microchip's FUSB board has such a mechanism. They use two inductors to couple and Vcc lines to board. But I cant find out the value of inductor.